blueovalz Posted June 2, 2001 Share Posted June 2, 2001 Messing around the salvage yard today and found 2 items that may be of interest to this site (my buddies) 1) I found a '95 Altima (not sure on the year or what model of Altima) that had the front rotors exactly identical to the older front Maxima rotors that I use on the rear of my Z (identical in every way) 2) Took a front rotor off a Supra (not current gen but the previous gen) that measured just under 12" X .8" (11.9"), and re-drilled the pattern to a four bolt pattern to match my Z. Slightly shaved the circumference of the Z hub, opened up the hub hole on the Supra caliper, slipped the rotor over the outside of the hub (just like current day cars do) and bolted it on. Took all of about 2 hours to do this correctly (with absolutely no run-out). Now I will find a way to match up a capliper, and I will have 1" larger rotors (than the 300ZX rotors currently on the front) on the front using salvage parts again. The ZX caliper I'm currently using could be modified to fit, but I'm going to try some other type. Anyway, the caliper needs only to be offset by about 5mm more toward the outside, and about 12mm radially, with this rotor than the ZX rotor provided for. And the wheel is now off-set about 6mm outward since the rotor fits between the hub and the wheel now. I'll find the exact year of the supra next week. Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted June 2, 2001 Share Posted June 2, 2001 Funny you should mention those Supra rotors Terry, I was at a wrecking yard with my younger brother today and saw one of those same cars(would say mid to late 80's) it was a turbo car and I pointed to the rotor and said "hmm, looks like a 12" rotor" those cars have beefy suspension also. Maybe I will go back and get them Keep us posted on the caliper issues. Jamie Deathstar Z Quote Link to comment Share on other sites More sharing options...
DavyZ Posted June 2, 2001 Share Posted June 2, 2001 Terry, I would LOVE to hear about this in detail after you have done some testing. Thanks for sharing the information! David Quote Link to comment Share on other sites More sharing options...
Modern Motorsports Ltd Posted June 2, 2001 Share Posted June 2, 2001 Thanks for the info Terry. Is their ever a balance issue present when redrilling rotors? I know the drilling is near the centre but still curious as rotors are all balanced typically, especially the larger diameter rotors. Do have a machine shop redrill or do you do it with a template and a drill press? Is that rotor a tight fit to your studs and are you running stock diameter studs? Thanks Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted June 3, 2001 Share Posted June 3, 2001 I think I have seen where BAER brakes uses late model Corvette rotors for most(maybe all) of its 12" brake conversions. I know for a fact that the ones they use on Mustang conversions are the vette parts re-drilled. I had them on my conv. stang. Jamie Deathstar Z Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted June 3, 2001 Share Posted June 3, 2001 Aw shoot, and I was getting excited about the 11inch solid rear rotors I'm going to be running. Do you know how much the rotors cost over the counter? Are they vented? Quote Link to comment Share on other sites More sharing options...
blueovalz Posted June 3, 2001 Author Share Posted June 3, 2001 What I did to drill the the stud holes was put bolt a four holer onto the five holer rotor with a single bolt (both are 4.5" patterns). Using the hub holes, and the hat parts to aline the two rotors, I marked the new holes, punched, and drilled (in 3 stages to make sure the bits were staying true to the punch) it on a press. Basically I used the four holed rotor (Maxima) as a template. I personally feel I was very lucky to get no run-out. It was perfect. I hope I have the same luck with the other side. The studs I'm using are 1/2" and the new holes are 1/2" too. This makes for zero play when the rotor slips over the studs and hub center. There is no balance issue here either. The rotors are the same thickness as the 300zx, and they are vented. Once I can get a caliper solution figured out, then I'll be more optimistic about these rotors as an option for the fiscally prudent. The 300zx rotors work fine, but I'm at the limit of valve adjustment, and would like more braking up front. At this stage it's only an experiment. Terry Quote Link to comment Share on other sites More sharing options...
DavyZ Posted June 3, 2001 Share Posted June 3, 2001 I qualify as one of the "fiscally prudent" as you say...thanks for the info, Terry! David--the fiscally prudent Zer Quote Link to comment Share on other sites More sharing options...
Modern Motorsports Ltd Posted June 3, 2001 Share Posted June 3, 2001 Not being nitpicky Terry but just don't fully understand.....how can you not have a balance issue if you have a non-symmetrical hole pattern/removal of metal? It had 5x4.5 and now has 4x4.5 so now has 8 holes which are not overall symmetrical. Or is this so slight it's negligible? Thanks Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted June 4, 2001 Share Posted June 4, 2001 It would seem to me that not only is it a slight amount of metal but that it's also in pretty close to the hub relatively speaking. In order for that little bit of weight to become an issue that hub would have to be really humming! Extrapolate out what the rim speed would be and wowza I don't think this is much different than drilling the hub flanges themselves which several of us have done, including myself. Mine's not on the road yet but others have made their maiden journies with no problems that I'm aware of. Can anyone comment? Quote Link to comment Share on other sites More sharing options...
Modern Motorsports Ltd Posted June 4, 2001 Share Posted June 4, 2001 I agree it's a small mass and less centripetal as it's near the rotation point but was curiuos I've had some vibrations in my car for a bit but have't had time to go thru and chase them all out...I suspect a rotor a redrilled kinda poorly might have some runout but that was a late night job that's had me rolling and having fun for well over a year now I had my first enjoyable use of a transfer punch today and look fwd to using it again on other projects (used it in mounting my new ECU). Quote Link to comment Share on other sites More sharing options...
PaulR Posted June 4, 2001 Share Posted June 4, 2001 I did some quick "back of the napkin" calculations and figured that removing a .5 inch dia cast iron slug, at a radius of 2.25 inch (half the bolt circle dia) would be balanced by adding a .05 ounce wheel weight at a radius of 7.5 inches (ie, a 15 inch wheel). I don't honestly know what wheels are typically balanced to, but I bet they don't get anywhere close to 5 hundreths of a ounce. So I would say the imbalanced caused by redrilling 4 to 5 lugs would be insignificant. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted June 5, 2001 Author Share Posted June 5, 2001 To answer the balance question, a 5 hole disc pattern, in itself, is balanced because all five are equally spaced. The same can be said for a 4 hole pattern. To visualize the combination, do a thought experiment where you take both discs, and put them on the same axis of rotation. Does adding both discs together cause the assembly to be out of balance? No, because both balance independently. The new holes may look asymetric with the old holes, but a careful analysis of the angles, and using some simple trig, it can be found that mathematically, they are "symetrical". Terry Quote Link to comment Share on other sites More sharing options...
blueovalz Posted June 8, 2001 Author Share Posted June 8, 2001 Update: I never do the the best thing first (except eat my cherry pie dessert first). When I adapted the '86 Supra 12" rotors onto the Z, I put them on the outside 'cause it worked good. I've now re-done the set-up to bolt onto the OEM rotor location behind the hub. I did this so that my options of a 4-puck caliper would be open. Anyway, At this time I have modified the strut for the attachment of the matching Supra caliper. I looked at one RX-7 4-puck caliper, but the pistons were only 1.375" in diameter (3" square for 2 pistons) and the Supra was a single 2.375" piston (4.4" square and same size as the 280ZX calipers). No contest on using the Supra instead of the RX7 calipers. Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted June 8, 2001 Share Posted June 8, 2001 Pics, want to see pics! Quote Link to comment Share on other sites More sharing options...
Ray Posted June 20, 2001 Share Posted June 20, 2001 opps [ June 19, 2001: Message edited by: Ray ] Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted June 20, 2001 Share Posted June 20, 2001 a willwood superlite 2 caliper will bolt to z spindle-maybe that would work on toy rotor. Quote Link to comment Share on other sites More sharing options...
jeromio Posted June 20, 2001 Share Posted June 20, 2001 Terry, when you say 4 puck, do you not mean 4 piston? In that case, would the RX7 caliper not be 6 inches of piston area (1.48 times 4)? For the "Second Method", I presume no mods to the hub are necessary? No way am I bold enough to drill out them holes my own self, but there's a local wheel shop that could probably do it. I am intrigued. The Oxandale ZCar R&D machine rolls onward.... Quote Link to comment Share on other sites More sharing options...
blueovalz Posted June 26, 2001 Author Share Posted June 26, 2001 Jeromio brought up an issue that was not replied to, and I wish to "confront" our technical best here: A single piston floating caliper has "x" square inches of area and moves "y" inches with each stroke of the master cylinder (squeezing against it's own frame). A 2 piston caliper (OEM Z caliper) as "2x" square inches of (assume both pistons are identical to the floater single piston) piston area, and each of these pistons only moves ".5y" inches per stroke of the master cylinder. Now add both sides (2 pistons) squeezing together and the total expansion of the pistons is now "y" inches, which is now the same squeeze distance as for the single floater per stroke. Thus I believe that in comparing single piston, vs multi-piston calipers, you compare the single piston size with only one side of the multi-piston calipers (or total of one side) size. Any engineers out there want to take this on and help us out? Oh yeah, No hub mods were necessary. Terry Quote Link to comment Share on other sites More sharing options...
jeromio Posted July 3, 2001 Share Posted July 3, 2001 Well, this didn't generate as much dicussion as I had hoped.... An opposing pair are clearly dependent upon each other since the caliper doesn't float, but their combined forces are not merely equal to the force of half the pair as a result. Another way to look it is that though the single piston is squeezing both sides, this does not "increase" it's clamping force as compared to the opposing pistons. Rather, since the single piston must "travel" twice as far to perform it's clamping, it would theoretically require more fluid to be pumped to it to provide the equivalent clamping force of a similar dual piston setup. IOWs, I'm suggestin (tentatively) that if X is piston diameter, a 4X single piston might be inferior to a 1X 4 Piston caliper. But at the least, it seems that the multi piston unit is equivalent when considering total piston area. Obviously none of my conjecture is based on any kind of research or engineering knowledge. Quote Link to comment Share on other sites More sharing options...
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